'sensitometer' originates from Modern English as a compound of 'sensitive' and the suffix '-meter'; 'sensitive' ultimately comes from Latin 'sensus' (via Latin 'sensibilis'), and '-meter' comes from Greek 'metron' meaning 'measure'.

'sensitometer' was coined as a technical photographic term in the late 19th to early 20th century by combining the adjective 'sensitive' with the measuring-suffix '-meter', forming a name for devices that measure photographic sensitivity.

Initially, it meant 'an instrument for measuring the sensitivity of photographic materials', and this technical meaning has largely remained unchanged into modern usage.